Kauntim mi tu, an integrated bio-behavioural survey (IBBS) of women and girls who sell and exchange sex (from here on referred to as FSW), and men who have sex with men and transgender women (from here on referred to as MSM/TG), was conducted to support the scale up of essential HIV prevention and treatment services for these populations. The survey was conducted in Port Moresby between June and November 2016 and used respondent-driven sampling (RDS) to recruit participants. Kauntim mi tu had two goals: 1) to conduct Papua New Guinea’s first population size estimations of FSW and MSM/TG; and 2) to collect representative bio-behavioural data about FSW and MSM/TG in order to inform HIV and STI prevention and treatment services and policy.